JPH05118290A - Cooling device for multi-stage vacuum pump - Google Patents

Abstract

PURPOSE:To make a vacuum pump compact by attaching a cooler as a separate component to a lower part of a pump casing to dispense with an intercooler, and to provide a multi-stage vacuum pump cooling device appropriate for discharging sublimational or condensational gas by not cooling a casing main body. CONSTITUTION:In a multi-stage vacuum pump cooling device for removing compression heat generated in a compression stroke of gas to be discharged, a cooler 16 for passing cooling water is provided in a lower part of a pump casing 1. The gas to be discharged is cooled via a wall body 15 in the lower part of the pump casing 1 by means of the cooler 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a multistage vacuum pump, and more particularly to a cooling device suitable for a multistage vacuum pump that exhausts a sublimable or condensable gas.

[0002]

2. Description of the Related Art Conventionally, there is known a multistage vacuum pump in which rotors having a plurality of rotors are provided adjacent to each other along a rotation axis, and the rotors facing each other rotate in opposite directions to perform suction and exhaust. ing. The rotor for a multi-stage vacuum pump rotates without contacting each other with a slight gap maintained between the rotors facing each other and between the rotor and the casing.

In the above-described multi-stage vacuum pump, a cooling device is provided for removing the compression heat generated in the compression process of the exhaust gas. As shown in FIG. 3, a conventional cooling device for a multi-stage vacuum pump includes a cooler 32 installed at a position separated from a casing 31 of the multi-stage vacuum pump, and the casing 31 and the cooler 32 are connected by a conduit 33. Was there. The cooler 32 is installed at each stage where cooling of the vacuum pump is required. The system shown in FIG. 3 is called an intercooler type.

Next, another cooling device in the conventional multistage vacuum pump will be described with reference to FIG. This cooling device is of a so-called jacket type and has water cooling chambers 41, 41 on both outer sides of the casing 31 of the multi-stage vacuum pump.
Is equipped with. As a result, the compression heat generated in each stage is cooled through the pump casing wall.

[0005]

However, in the cooling device for the multi-stage vacuum pump shown in FIG. 3 described above, since the cooler is installed at each stage apart from the casing, a large installation space is required. However, there is a problem in that the entire apparatus of the multi-stage vacuum pump becomes large as a result.
Further, since the cooling device is separately installed at a position separated from the vacuum pump in this way, there is a problem that the entire device becomes expensive.

On the other hand, in the jacket type cooling device shown in FIG. 4, since the casing main body is directly cooled by the cooling material, the substance sublimated or condensed in the cooling portion adheres and accumulates between the rotor and the casing. This condensate has a problem that the pump may be overloaded or stopped.

The present invention has been made in view of the above-mentioned points, and its object is to eliminate the need for an intercooler by attaching a cooler to the lower portion of the pump casing.
Another object of the present invention is to provide a cooling device for a multistage vacuum pump which can be made compact and which is suitable for exhausting a sublimable or condensable gas by not cooling the casing body.

[0008]

In order to achieve the above-mentioned object, a cooling device for a multi-stage vacuum pump according to the present invention is a cooling device for a multi-stage vacuum pump for removing compression heat generated in a compression process of exhaust gas. In the above, a cooler for passing cooling water is provided in a lower portion of the pump casing, and the exhaust gas is cooled by the cooler through a wall body provided in a lower portion of the pump casing. Is.

[0009]

According to the cooling device for a multi-stage vacuum pump of the present invention having the above-described structure, a cooler is attached to the lower portion of the pump casing as a separate component, and cooling water is passed through this cooler to be provided at the lower portion of the pump casing. By cooling the gas exhausted through the enclosed wall body at each stage, an intercooler is not required and the vacuum pump can be made compact, and by not cooling the casing body, sublimation or condensability It is possible to prevent the gas of the above from condensing in the casing.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cooling device for a multistage vacuum pump according to the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram showing the overall structure of a vacuum pump incorporating the cooling device according to the present invention, and FIG. 2 is a line II in FIG.
It is a sectional view taken along the line II.

In FIGS. 1 and 2, reference numeral 1 is a casing, and a pair of rotating bodies 2 and 2 are arranged in the casing 1. The rotating body 2 includes a rotating shaft 3 and a plurality of rotors 4 arranged along the axial direction of the rotating shaft. The rotating body 2 is rotatably supported by a bearing 5 at one end thereof and a bearing 6 at the other end thereof, and one rotating body 2 is connected to a motor 7. Then, from one rotating body 2 to the other rotating body 2
Is transmitted by a gear 8 (only one gear is shown in FIG. 1) fixed to the shaft end of the rotary shaft 3,
The pair of rotating bodies 2 and 2 rotate in mutually opposite directions, and the rotors 4 and 4 facing each other with a small gap rotate in mutually opposite directions to perform intake and exhaust.

The bearing 5 is housed in the bearing case 10, and the bearing 6 and the gear 8 are housed in the bearing case 11. The bearings 5 and 6 and the gear 8 are lubricated by the lubricating oil in the bearing cases 10 and 11.

At the lower part of the pump casing 1, a lower wall body 15 is provided so as to close the opening 1a of the pump casing. A cooler 16 is attached to the lower wall body 15. Cooling water is passed through the cooler 16. This cooler 16 removes the compression heat of the gas exhausted from each stage. That is, as shown by arrows A and B in FIG. 2, the exhaust gas discharged from each stage once comes into contact with the lower wall body 15 and then rises to be guided to the rotor chamber of the next stage. . When the exhaust gas comes into contact with the lower wall body 15, the exhaust gas is cooled through the wall body by the cooling water passing through the cooler 16. As described above, in this embodiment, since the cooler 16 is installed in the lower part of the pump casing 1, even if the sublimable or condensable exhaust gas is cooled and condensed by the cooler 16, the condensate is condensed. Will accumulate on the upper surface of the lower wall 15 below the pump casing 1, and there is no risk of accumulation between the rotor 4 and the pump casing 1.

Next, the flow path of the gas exhausted by the vacuum pump will be briefly described. The pump suction port 12
The gas flowing into the casing is moved from the top to the bottom by the rotor 4 for each stage. At this time, the gas is compressed, so the temperature rises due to the heat of compression. After that, the gas comes into contact with the lower wall body 15 having the cooler 16 which is provided at the lower part of the pump casing 1 and which allows the cooling water to pass therethrough, heat exchange is performed at the time of contact, and the exhaust gas is cooled. It At this time, in the case of a sublimable or condensable gas, there is a possibility that it will condense and accumulate on the lower wall body 15 as a condensate, but this lower wall body 15 is slightly separated from the pump casing 1. Since it is installed in such a position, there is no possibility that condensed matter condensed between the rotor 4 and the casing 1 will be accumulated. In this way, for sublimable or condensable gases,
Since the cooler is not adjacent to the casing body and is located below the pump casing, the pump body can discharge the gas without being affected by the substance sublimated and condensed by the cooler.

Further, in the case of exhausting a gas that is not sublimable or condensable, a cooler can be attached to the inlet plate or the like at the upper part of the pump.

[0017]

As described above, according to the cooling device for a multi-stage vacuum pump of the present invention, a cooler is attached to the lower portion of the pump casing as a separate component, and cooling water is passed through this cooler to lower the lower portion of the pump casing. By cooling the gas exhausted through the wall body provided in each stage, an intercooler is not required and the vacuum pump as a whole can be made compact.

Further, according to the present invention, since the casing body is not cooled, it is possible to avoid condensation of the sublimable or condensable gas in the casing, which is extremely suitable for the sublimable or condensable exhaust gas.

[Brief description of drawings]

FIG. 1 is a sectional view showing an overall configuration of a multistage vacuum pump including a cooling device according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a cross-sectional view showing a conventional cooling device for a multi-stage vacuum pump.

FIG. 4 is a sectional view showing another cooling device of the conventional multistage vacuum pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Rotating body 3 Rotating shaft 4 Rotor 5,6 Bearing 7 Motor 8 Gear wheel 10,11 Bearing case 15 Lower wall body 16 Cooler

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuaki Usui 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Stock company EBARA Research Institute

Claims (1)

[Claims] 1. A cooling device for a multi-stage vacuum pump for removing heat of compression generated in a compression process of exhaust gas, wherein a cooler for passing cooling water is provided below a pump casing, and by this cooler, A cooling device for a multi-stage vacuum pump, wherein the exhaust gas is cooled through a wall provided at a lower portion of the pump casing.